This invention relates generally to wind turbines and more particularly, to a system for heating and cooling wind turbine components.
Generally, a wind turbine includes a rotor having multiple blades. The blades are attached to a rotatable hub, and the blades and hub are often called the rotor. The rotor transforms mechanical wind energy into a mechanical rotational torque that drives one or more generators. The generators are generally, but not always, rotationally coupled to the rotor through a gearbox. The gearbox steps up the inherently low rotational speed of the turbine rotor for the generator to efficiently convert the rotational mechanical energy to electrical energy, which is fed into a utility grid. Gearless direct drive wind turbine generators also exist. The rotor, generator, gearbox and other components are typically mounted within a housing, or nacelle, that is positioned on top of a base that may be a truss or tubular tower.
The gearboxes need to be lubricated and cooled to function effectively. Typically, oils are used for lubrication in a gearbox, and the oil heats up during operation of the gearbox. A heat exchanger is typically used to cool the oil, and an oil-to-air radiator or heat exchanger is commonly used to dissipate heat from the lubricating oil. Electrical generators also need to be cooled and air-to-air or water-to-air heat exchangers have been employed to dissipate the heat from the generators housed within the nacelle.
In some known systems, the gearbox and generator have their own separate heat exchangers. For example, in one known system a gearbox heat exchanger includes a fan, ductwork, and an oil-to-air heat exchanger. The generator heat exchanger includes another fan, additional ductwork and an air-to-air heat exchanger. Air for both separate heat exchangers is typically drawn from the air within the nacelle. During operation of the wind turbine, many components generate heat and the temperature of the air within the nacelle can be elevated with respect to the outside ambient air. This can result in in-efficiencies in the cooling system by using warmed air to cool hot components.